What is the action of the long digital extensor muscle?

• A. Flex tarsus, pronate pes
• B. Extend tarsus, extend digits II-V
• C. Flex stifle, extend tarsus
• D. Flex metatarsophalangeal joints

Answer: (B)

The long digital extensor muscle's primary action is to extend the tarsus and extend the digits II-V. This muscle plays a crucial role in movements that require the extension of the toes, particularly during activities such as running and walking. When the long digital extensor contracts, it helps to lift the toes and foot up, which is essential for proper locomotion. Additionally, the extension of the tarsus is important for stabilizing the hind limb during movement.

The other options describe actions that do not align with the primary function of the long digital extensor. The muscle does not flex the tarsus or pronate the pes, as outlined in some of the incorrect choices. Instead, its specific anatomical and functional characteristics are aligned solely with the extension of the tarsus and digits II-V. This focus on extension sets the long digital extensor apart from other muscles that may engage in flexion or different movements at the joints.